The invention relates to superconductor cables and magnetic devices.
Multi-layer superconductor articles, such as tapes, having various architectures have been developed. Such articles often include a substrate and a superconductor layer. Typically, one or more buffer layers are disposed between the substrate and the superconductor layer.
In general, the invention relates to superconductor cables and magnetic devices.
In one aspect, the invention features an article that includes a first layer formed of a first superconductor material and a second layer formed of a first electrically conductive material. The article also includes a third layer formed of a second superconductor material and a fourth layer formed of a second electrically conductive material. The second layer is mechanically coupled to the first layer (e.g., mechanically coupled at points other than their ends), and the fourth layer is mechanically coupled to the third layer (e.g., mechanically coupled at points other than their ends). The second and fourth layers are in electrical communication. The first and second layers have a neutral mechanical axis when bent that is different than the neutral mechanical axis of the third and fourth layers when bent.
The phrase xe2x80x9cmechanically coupled,xe2x80x9d as used herein, refers to a force between (e.g., at the interface of) two layers that substantially reduces (e.g., eliminates) the ability of one layer to move independently of the other layer. One example of mechanically coupled layers is two layers that are chemically bonded together. Another example of mechanically coupled layer is two layers that are metallurgically bonded together. An additional example of mechanically coupled layers is two layers that are each adhered to an adhesive layer therebetween. It is to be noted that two layers (or other articles, such as tapes) generally are not mechanically coupled when the layers (or articles) are held in compression against each other by a force acting from outside (as opposed to at the interface of) the two layers. For example, if two tapes are wrapped within insulation that provides a compressive force that holds the tapes in proximity to each other, this force itself does not render the tapes mechanically coupled, although the tapes may otherwise be mechanically coupled (e.g., if the tapes are chemically or metallurgically bonded to each other).
The article can be configured so that the second and fourth layers can move independently of each other.
The first and second superconductor materials can be the same or different. For example, one or both of the superconductor materials can be a rare earth superconductor material, such as YBCO.
The first and second electrically conductive materials can be the same or different. For example, the first and second electrically conductive materials can be a metal (e.g., copper) or an alloy (e.g., a copper alloy).
The first and second layers can be in the form of a tape. The second and third layers can be in the form of a tape.
The article can further include first and second substrates. The first layer can be between the first substrate and the second layer, and the third layer can be between the second substrate and the fourth layer.
The article can further include first and second buffer layers. The first buffer layer can be between the first substrate and the first layer, and the second buffer layer can be between the second substrate and the third layer.
In some embodiments, the first substrate layer has a thickness that is about equal to a combined thickness of the first layer, the first buffer layer, and the second layer.
In certain embodiments, the fourth layer has a thickness that is about equal to a combined thickness of the third layer, the second buffer layer, and the second substrate layer.
The article can further include first and second cap layers. The first cap layer can be between the first and second layers, and the second cap layer can be between the third and fourth layers.
The article can further include an interfacial layer between the second and fourth layers. The interfacial layer is generally formed of an electrically conductive material and can be, for example, capable of reducing oxidation of the second and fourth layers, and/or reducing friction between the second and the fourth layer. In some embodiments, the interfacial layer is at least partially formed or graphite.
In another aspect, the invention features an article (e.g., a cable) that includes first and second helically wound superconductor tapes. The first tape includes a superconductor layer and an electrically conductive layer, and the second tape that includes a superconductor layer and an electrically conductive layer. The electrically conductive layers of the first and second tapes ar in electrical communication (e.g., in electrical communication at more than one position, such as by contacting each other in more than one location). The first helically wound superconductor tape has a neutral mechanical axis, and the second helically wound superconductor tape has a different neutral mechanical axis.
The first and second helically wound tapes can be configured so that they can move independently of each other.
The article can further include a forming element around which the first and second tapes are helically wound.
In some embodiments, the superconductor layers of the first and/or second superconductor tapes are mechanically compressed.
The first and second helically wound superconductor tapes can have a common helical axis.
In some embodiments, the article further includes third and fourth helically wound superconductor tapes. The third helically wound superconductor tape includes a superconductor layer and an electrically conductive layer, and the fourth helically wound superconductor tape includes a superconductor layer and an electrically conductive layer. The electrically conductive layers of the third and fourth superconductor tapes have more than one point of electrical communication (e.g., by contacting each other in more than one location). The third and fourth helically wound superconductor tapes can have a common helical axis.
In certain embodiments, the electrically conductive layers of the first and second superconductor tapes at least partially overlap. In some embodiments, the electrically conductive layers of the first and second superconductor tapes substantially entirely overlap.
In a further aspect, the invention features an article that includes first and second pluralities of helically wound tapes. In the first plurality of helically wound superconductor tapes, each tape includes a layer of a superconductor material and a layer of an electrically conductive material, and each tape is wound in parallel in a first direction. In the second plurality of helically wound superconductor tapes, each tape includes a layer of a superconductor material and a layer of an electrically conductive material, and each tape is wound in parallel in a second direction opposite the first direction. The layer of the electrically conductive materials in each tape in the first plurality of tapes has more than one position of electrical communication with the layer of electrically conductive material in each tape of the second plurality of tapes (e.g., by contacting each other in more than one location).
In some embodiments, the first and second pluralities of helically wound superconductor tapes have a common helical axis.
In certain embodiments, the electrically conductive layers of each tape in the first plurality of superconductor tapes at least partially overlap with the electrically conductive layers of each tape in the second plurality of superconductor tapes.
Each of the tapes in the article can have a different neutral mechanical axis when bent than the neutral mechanical axis of any of the other tapes when bent.
In an additional aspect, the invention features a superconducting magnetic coil that includes first and second coiled superconductor tapes. Each coiled superconductor tape is coiled about a respective coil axis. The first coiled superconductor tape includes a superconductor layer and an electrically conductive layer. The electrically conductive layer of the first coiled superconductor tape has a surface that forms an inner surface of the first coiled superconductor tape. The inner surface of the first coiled superconductor tape faces the coil axis of the first coiled superconductor tape. The second coiled superconductor includes a superconductor layer and an electrically conductive layer. The electrically conductive layer of the second coiled superconductor tape has a surface that forms an outer surface of the second coiled superconductor tape. The outer surface of the second coiled superconductor tape faces away from the coil axis of the second coiled superconductor tape. The first and second coiled superconductor tapes are configured so that inner surface of the first superconductor tape is adjacent the outer surface of the second superconductor tape.
The first and second superconductor tapes in the magnetic coil can have different neutral mechanical axes from each other.
In some embodiments, the first and second coiled superconductor tapes contact each other.
In certain embodiments, the first and second coiled superconductor tapes are wound together.
In some embodiments, the coil axis of the first superconductor tape is the same as the coil axis of the second superconductor tape.
In certain embodiments, the first and second superconductor tapes are coiled about each other.
In some embodiments, the superconductor layer and electrically conductive layer of the first superconductor tape are mechanically coupled (e.g., mechanically coupled at points other than their ends), and the superconductor layer and electrically conductive layer of the second superconductor tape are mechanically coupled (e.g., mechanically coupled at points other than their ends).
In certain embodiments, the superconductor layers of the first and/or second superconductor tapes are mechanically compressed.
The superconducting magnetic coil can further include an interfacial layer disposed between the adjacent first and second superconductor tapes.
The superconducting magnetic coil can further include third and fourth coiled superconductor tapes. Each of the third and fourth coiled superconductor tapes is coiled about a respective coil axis. The third coiled superconductor tape includes a superconductor layer and an electrically conductive layer. The electrically conductive layer of the third coiled superconductor tape has a surface that forms an inner surface of the third coiled superconductor tape. The inner surface of the third coiled superconductor tape faces the coil axis of the third coiled superconductor tape. The fourth coiled superconductor includes a superconductor layer and an electrically conductive layer. The electrically conductive layer of the fourth coiled superconductor tape has a surface that forms an outer surface of the fourth coiled superconductor tape. The outer surface of the fourth coiled superconductor tape faces away from the coil axis of the fourth coiled superconductor tape. The third and fourth coiled superconductor tapes are configured so that inner surface of the third superconductor tape is adjacent the outer surface of the fourth superconductor tape.
The architecture of the superconductor articles (e.g., tapes, cables and/or magnetic coils) can allow multiple superconductor layers to simultaneously be compressed (e.g., by being at or below the neutral mechanical axis) when the articles are bent.
The architecture of the superconductor articles (e.g., tapes, cables and/or magnetic coils) can reduce the risk of reduced current density due to, for example, the presence of defects (e.g., localized defects, such as a crack a grain boundary, or the like) in one or more of the superconductor layers.
The architecture of the superconductor articles (e.g., tapes, cables and/or magnetic coils) can result in current sharing through, for example, redundant conducting paths, lower hysteretic losses under alternating current conditions, enhanced electrical stability, and/or enhanced thermal stability.
The architecture of the superconductor articles (e.g., tapes, cables and/or magnetic coils) can result in a favorable stress profile and/or improved mechanical properties.
The architecture of the superconductor articles (e.g., tapes, cables, and/or magnetic coils) can provide improved mechanical stability, improved electrical stability, enhanced current carrying capacity, and/or favorable economy of manufacture.
The architecture of the superconductor articles (e.g., tapes, cables and/or magnetic coils) can reduce mechanical degradation of the operational superconductor layer(s) during bending.
The architecture of the superconductor articles (e.g., tapes, cables and/or magnetic coils) can make it relatively easy to splice the articles.
The architecture of the superconductor articles (e.g., tapes, cables and/or magnetic coils) can make it relatively easy to achieve termination of tape stack ups and/or conductor elements.
The architecture of the superconductor articles (e.g., tapes, cables and/or magnetic coils) can reduce heating due to, for example, localized defects in the superconductor material.
The superconductor articles (e.g., tapes, cables and/or magnetic coils) can be used in a variety of applications, including, for example, electrical, magnetic, electro-optic, dielectric, thermal, mechanical, and/or environmental (e.g., protective) applications.
Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.